On display devices such as a liquid crystal display (LCD), a tape carrier package (TCP) is mounted. The tape carrier package includes on a tape carrier thereof an IC chip (semiconductor device) that will become a display driver. In such a TCP, with a larger size and a higher definition of a panel, the number of outputs of the IC chip has been increased for implementing a configuration of multi-channels (800 to 1000 ch). Then, pitches of lead patterns on the tape carrier have been become narrower and narrower. In the IC chip where the number of outputs has increased for implementing the multi-channel configuration, the amount of heat generation increases due to an increase in an operation load. For this reason, in the TCP, heat dissipation as the package becomes important so as to stabilize an operation of the IC chip.
Heat generated in the IC chip is discharged outside the TCP mainly through lead patterns of the TCP. This is because a conductor (made of a copper foil or the like) has a higher heat conductivity than a tape substrate (made of polyimide, or the like). Accordingly, in order to increase the heat dissipation of the TCP, an increase in volume and surface area of the lead patterns becomes effective means.
Among conventional TCPs, there is a TCP in which for increasing the surface area of the lead patterns (conductor patterns), second conductor patterns 108 that do not substantially play a role in signal input and output for a semiconductor 102 (IC chip) are formed on a blank area on which no first conductor pattern 107 for signal input and output for the, semiconductor device 102 is arranged. Element 106 represents an input lead, and element 115 represents an insulation layer (refer to FIGS. 7 and 8; and refer to Patent Documents 1 and 2).
[Patent Document 1]
JP Patent Kokai Publication No. JP-P-2004-111996A
[Patent Document 2]
JP Patent Kokai Publication No. JP-A-10-32229
[Patent Document 3]
JP Patent Kokai Publication No. JP-A-3-57248
[Patent Document 4]
JP Patent Kokai Publication No. JP-A-2-155248